Make it so property seed supports dotted property gets.

This allows e.g. `a.2` to select from {a: [0,1,2]} to return 2.

Part of #50.

README.md

@@ -496,7 +496,7 @@ Selects a named property from an object
 
 Required parameters:
 - `object` - The object to select a property from. If some of the sub-keys need to be computed, nest a sub-seed of type `object`.
-- `property` - The property to select from the object.
+- `property` - The property to select from the object. It can be a "dotted" property to retrieve sub objects. For example `a.2` would fetch the `a` property from the object and then the `2` property from that object. (Note that due to the way that javascript handles arrays, fetching numbered items from an array works).
 
 #### keys
 

src/grow.ts

@@ -54,7 +54,7 @@ import {
 } from './types.js';
 
 import {
-	assertUnreachable
+	assertUnreachable, getObjectProperty
 } from './util.js';
 
 import {
@@ -425,8 +425,7 @@ const growProperty = async (seed : Seed<SeedDataProperty>, env : Environment) :
 	const property = extractString(await getProperty(seed, env, data.property));
 	//obj might be an object, an array, or even an embedding. Whatever!
 
-	//eslint-disable-next-line @typescript-eslint/no-explicit-any
-	return (obj as any)[property];
+	return getObjectProperty(obj as {[name : string]: unknown}, property) as Value;
 };
 
 const growKeys = async (seed : Seed<SeedDataKeys>, env : Environment) : Promise<Value> => {

test/base/a_test.json

@@ -337,6 +337,17 @@
                 "two"
             ],
             "delimiter": ":"
+        },
+        "dotted-property-test": {
+            "type": "property",
+            "object": {
+                "a": [
+                    0,
+                    1,
+                    2
+                ]
+            },
+            "property": "a.1"
         }
     }
 }

test/base/test.ts

@@ -919,6 +919,14 @@ Suffix`;
 		assert.deepStrictEqual(actual, golden);
 	});
 
+	it('dotted property test', async () => {
+		const garden = loadTestGarden();
+		const seed = await garden.seed('dotted-property-test');
+		const actual = await seed.grow();
+		const golden = 1;
+		assert.deepStrictEqual(actual, golden);
+	});
+
 });
 
 describe('expandSeedPacket tests', () => {